Multistage combustor and method for starting a fuel cell system

Abstract

A multistage combustor is configured for starting a fuel cell system, and includes a partial oxidation (POX) burner having an inlet for receiving a flow of a fuel/oxidant mixture, the POX burner being configured to partially oxidize fuel in the fuel/oxidant mixture to yield a partially oxidized gas; a first output coupled to the fuel cell system and configured to provide a first amount of the partially oxidized gas as first output gas to a first fuel cell system component; a second burner coupled to the POX burner, the second burner being configured to receive a second amount of the partially oxidized gas from the POX burner and to oxidize at least some remaining fuel to yield a second output gas different from the first output gas; and a second output coupled to a second fuel cell system component and configured to provide the second output gas to the second fuel cell system component.

What is claimed is: 
     
       1. A multistage combustor configured for starting a fuel cell system, said fuel cell system including a first component and a second component, comprising:
 a partial oxidation (POX) burner having an inlet for receiving a flow of a fuel/oxidant mixture, said POX burner being configured to partially oxidize a fuel in said fuel/oxidant mixture to yield a partially oxidized gas; 
 a first output coupled to said fuel cell system and configured to provide a first amount of said partially oxidized gas as a first output gas from said multistage combustor to said first component; 
 a second burner coupled to said POX burner, said second burner being configured to receive a second amount of said partially oxidized gas from said POX burner and to oxidize at least some of a remaining fuel in said second amount of said partially oxidized gas to yield a second output gas from said multistage combustor different from said first output gas; and 
 a second output coupled to said second fuel cell system component and configured to provide said second output gas to said second fuel cell system component. 
 
     
     
       2. The multistage combustor of  claim 1 , wherein said POX burner is a premix burner, further comprising a preheater configured to preheat said fuel/oxidant mixture using heat released during the partial oxidation of said fuel in said POX burner. 
     
     
       3. The multistage combustor of  claim 1 , wherein said POX burner is configured to perform flame burning of said fuel/oxidant mixture, and wherein said second burner is a catalytic burner configured to oxidize said at least some of said remaining fuel using a catalytic combustion process. 
     
     
       4. The multistage combustor of  claim 1 , further comprising a second inlet coupled to said second burner and configured to supply a secondary oxidant flow to said second burner. 
     
     
       5. The multistage combustor of  claim 4 , wherein said second burner is configured to completely oxidize said second amount of said partially oxidized gas using said secondary oxidant flow to yield said second output gas. 
     
     
       6. The multistage combustor of  claim 5 , wherein said second fuel cell system component is a recuperator configured to extract heat from said second output gas for use in said fuel cell system. 
     
     
       7. The multistage combustor of  claim 1 , wherein said first component is an anode, wherein said fuel cell system further includes at least one of a vaporizer/mixer and a reformer, and wherein said first output provides said first output gas to said anode via said at least one of said vaporizer/mixer and said reformer. 
     
     
       8. The multistage combustor of  claim 1 , wherein said fuel is at least one of a liquid and a gas. 
     
     
       9. A fuel cell system, comprising:
 an anode; 
 a cathode fluidly coupled to a source of a normal cathode oxidant, said cathode being permeable to oxygen ions received from said normal cathode oxidant; 
 an electrolyte in communication with said anode and said cathode, said electrolyte being configured to supply said oxygen ions from said cathode to said anode; 
 a reformer fluidly coupled to said anode, said reformer being configured to receive a normal operating fuel and a normal reformer oxidant, and to generate a synthesis gas from said normal operating fuel and said normal reformer oxidant for use by said anode; 
 a recuperator configured to recapture waste heat for use in said fuel cell system; and 
 a multistage combustor configured for starting said fuel cell system, said multistage combustor including:
 a partial oxidation (POX) burner having a first inlet for receiving a flow of a starting fuel/oxidant mixture, said POX burner being configured to partially oxidize a starting fuel in said starting fuel/oxidant mixture to yield a partially oxidized gas; 
 a first output coupled to said fuel cell system and configured to provide a first amount of said partially oxidized gas as a first output gas from said multistage combustor to said reformer, said first output gas being configured to start a reaction in said reformer; 
 a second burner coupled to said POX burner, said second burner being configured to receive a second amount of said partially oxidized gas from said POX burner and to oxidize at least some of a remaining starting fuel in said second amount of said partially oxidized gas to yield a second output gas from said multistage combustor different from said first output gas; and 
 a second output coupled to said recuperator and configured to provide said second output gas to said recuperator. 
 
 
     
     
       10. The fuel cell system of  claim 9 , wherein said normal operating fuel and said starting fuel are a same fuel. 
     
     
       11. The fuel cell system of  claim 9 , wherein said starting fuel/oxidant includes said starting fuel and a starting oxidant, and wherein each of said starting oxidant and said cathode oxidant employs the oxygen in air. 
     
     
       12. The fuel cell system of  claim 11 , wherein said normal reformer oxidant includes the oxygen in air. 
     
     
       13. A combustor for starting a fuel cell system, comprising:
 a premix partial oxidation (POX) burner, said premix POX burner having a housing, a reaction zone defined in said housing; an igniter; and an inlet configured to receive a flow of a fuel/oxidant mixture into said reaction zone, said premix POX burner being configured to ignite and partially oxidize a fuel in said fuel/oxidant mixture in said reaction zone to yield a partially oxidized gas; 
 a first output configured to discharge a first amount of said partially oxidized gas to said fuel cell system from said premix POX burner as a first output gas of said combustor; and 
 a second output configured to discharge a second amount of said partially oxidized gas from said premix POX burner. 
 
     
     
       14. The combustor of  claim 13 , further comprising:
 a second burner coupled to said second output, said second burner being configured to receive said second amount of said partially oxidized gas from said premix POX burner and 
 to oxidize at least some of a remaining fuel in said second amount of said partially oxidized gas to yield a second output gas of said combustor different from said first output gas; and 
 a third output configured to discharge said second output gas to said fuel cell system. 
 
     
     
       15. The combustor of  claim 13 , further comprising a preheater configured to preheat said fuel/oxidant mixture using heat generated in said reaction zone during the partial oxidation of said fuel. 
     
     
       16. The combustor of  claim 15 , wherein said preheater is a conduit having a length disposed along said housing, and wherein said length is configured to limit a formation of carbon deposits around said inlet. 
     
     
       17. The combustor of  claim 15 , further comprising a liner disposed within said housing and defining said reaction zone. 
     
     
       18. The combustor of  claim 17 , further comprising an insulating material disposed between said liner and said housing.